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Use C# to get JSON Data from the Web and Map it to .NET Class => Made Easy!

, 12 Feb 2014 CPOL 224.4K 103
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Easy steps on how to get JSON formatted data from a web service, deserialize it, and map it to custom local class for further usage


This tip/trick demonstrates a complete and easy solution on how to get JSON formatted data from a web service, and map (deserialize) it to custom .NET class for further usage.

Sample Data

As an example, we will use service which provides latest currency rates formatted as JSON data. Here is a sample of how that data looks like:  

  "disclaimer": "This data is collected from various providers ...",
  "license": "Data collected from various providers with public-facing APIs ...",
  "timestamp": 1336741253,
  "base": "USD",
  "rates": {
    "AED": 3.6731,
    "AFN": 48.419998,
    "ALL": 107.949997,
    "AMD": 393.410004,
    "ANG": 1.79,
    "AOA": 94.949997,
    // ... more values ...

So, how do we retrieve them through C# on the server side and use them? Read on to find out.

How To - Three Easy Steps

Step 1. Install Json.Net library

Json.NET library provides an easy, and de-facto, standard way to convert (serialize) .NET class to JSON data, and JSON data back to .NET class (deserialize). 

The easiest way to install Json.Net library into your .NET project is via NuGet Package Manager Console by running this command:

install-package Newtonsoft.Json 

Alternatively, if you need to install it manually, download it from its project page on CodePlex.

Step 2. Create .NET class which will match JSON data format

If you are using Visual Studio 2012+, you're in luck, since you can just paste a sample JSON data and it will create a class for you, To do that, first create a new class .cs file, select it in project explorer, than copy sample JSON data to clipboard, go to EDIT > Paste Special > Paste JSON as classes (thanks to Dave Kerr for this tip). More information on this feature here

If that won't work for you, or you'd prefer to do it yourself, you'll need to define .NET class manually. It must exactly match the format of JSON data provided by  

public class CurrencyRates {
  public string Disclaimer { get; set; }
  public string License { get; set; }
  public int TimeStamp { get; set; }
  public string Base { get; set; }
  public Dictionary<string, decimal> Rates { get; set; }

Note that property names are not case sensitive, but the name has to exactly match the JSON one. Also, notice how "rates" JSON property is matched to a Dictionary<string, decimal>. If "rates" would have a singular value, they could alternatively be matched to an Array or IEnumerable.

Step 3. Create a method to retrieve JSON data and map it to .NET class

Now we will create the following universal method that can be re-used for any .NET class, where 'T' represents any .NET class that you need JSON data to be mapped to:

using System.Net;
using Newtonsoft.Json;

// ...

private static T _download_serialized_json_data<T>(string url) where T : new() {
  using (var w = new WebClient()) {
    var json_data = string.Empty;
    // attempt to download JSON data as a string
    try {
      json_data = w.DownloadString(url);
    catch (Exception) {}
    // if string with JSON data is not empty, deserialize it to class and return its instance 
    return !string.IsNullOrEmpty(json_data) ? JsonConvert.DeserializeObject<T>(json_data) : new T();

Here, at first, an instance of WebClient() System.Net class (a part of the .NET) downloads data from the specific URL as a plain string

Then, this string containing JSON data is mapped (deserialized) to any .NET class provided (CurrencyRates in our case). 

Deserialization is done via Json.NET library's method JsonConvert.DeserializeObject<T>(json_data), which attempts to match all JSON fields to the same .NET class fields. 

In this example, a call to a universal method _download_serialized_json_data<T>() can look like this:  

var url = " ";
var currencyRates = _download_serialized_json_data<CurrencyRates>(url); 

(Please note: if you want to use data provided by, first you need to get your unique App Id here:^, than replace YOUR_APP_ID in the sample above.) 

Final Note 

And that's it! Now you can do anything you need with the data you've just retrieved. 

Good luck!



This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Web Developer
United States United States
Coding is awesome!

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Comments and Discussions

GeneralRe: 'Paste JSON As Classes' in Visual Studio Pin
Mikhail Tsennykh30-Apr-13 4:30
memberMikhail Tsennykh30-Apr-13 4:30 
GeneralRe: 'Paste JSON As Classes' in Visual Studio Pin
Dave Kerr30-Apr-13 4:37
mvpDave Kerr30-Apr-13 4:37 
QuestionExample for POST JSON Pin
developer24724-Jan-13 13:49
memberdeveloper24724-Jan-13 13:49 
QuestionMultilayered JSON results Pin
John Mike H.19-Nov-12 9:03
memberJohn Mike H.19-Nov-12 9:03 
AnswerRe: Multilayered JSON results Pin
Mikhail Tsennykh19-Nov-12 11:27
memberMikhail Tsennykh19-Nov-12 11:27 
GeneralRe: Multilayered JSON results Pin
John Mike H.20-Nov-12 3:58
memberJohn Mike H.20-Nov-12 3:58 
QuestionMixed JSon to Object Pin
rhythmdivine7-Oct-12 3:27
memberrhythmdivine7-Oct-12 3:27 
AnswerRe: Mixed JSon to Object Pin
Mikhail Tsennykh7-Oct-12 7:05
memberMikhail Tsennykh7-Oct-12 7:05 
No problem! Smile | :)

Here you go:
using Newtonsoft.Json; // Json.Net library
using System.Collections.Generic;
using System.Collections.ObjectModel;
// ...

public List<Users> MapUsers() {
    var json_data = "[{\"UserId\":1,\"LoginId\":\"abc\",\"FirstName\":\"Rupak Kumar\",\"LastName\":\"Das\",\"Roles\":[{\"UserRoleId\":1,\"UserRoleName\":\"ReadOnly\"},{\"UserRoleId\":2,\"UserRoleName\":\"Edit\"}]}]";
    List<Users> users = JsonConvert.DeserializeObject<List<Users>>(json_data);
    return users;
This will return a list of you Json data mapped to your Users class. Just give it your source Json string instead of static variable, and you'll be good to go. I tested that in a sample project with the latest version of Json.Net library and it works great!

Good luck!
GeneralRe: Mixed JSon to Object Pin
rhythmdivine7-Oct-12 10:12
memberrhythmdivine7-Oct-12 10:12 
GeneralRe: Mixed JSon to Object Pin
Mikhail Tsennykh9-Oct-12 11:14
memberMikhail Tsennykh9-Oct-12 11:14 
GeneralRe: Mixed JSon to Object Pin
rhythmdivine24-Apr-14 5:21
memberrhythmdivine24-Apr-14 5:21 
GeneralMy vote of 5 Pin
manoj kumar choubey18-Jul-12 20:49
membermanoj kumar choubey18-Jul-12 20:49 
QuestionWhy ? DataContractJsonSerializer works fine. Pin
Nicolas Dorier6-Jun-12 4:01
memberNicolas Dorier6-Jun-12 4:01 
AnswerRe: Why ? DataContractJsonSerializer works fine. Pin
Mikhail Tsennykh6-Jun-12 6:37
memberMikhail Tsennykh6-Jun-12 6:37 
GeneralRe: Why ? DataContractJsonSerializer works fine. Pin
Nicolas Dorier6-Jun-12 7:14
memberNicolas Dorier6-Jun-12 7:14 
GeneralMy vote of 5 Pin
Othello744-Jun-12 21:40
memberOthello744-Jun-12 21:40 
GeneralRe: My vote of 5 Pin
Mikhail Tsennykh5-Jun-12 6:17
memberMikhail Tsennykh5-Jun-12 6:17 
GeneralMy vote of 5 Pin
parvus4-Jun-12 11:30
memberparvus4-Jun-12 11:30 
GeneralRe: My vote of 5 Pin
Mikhail Tsennykh4-Jun-12 11:47
memberMikhail Tsennykh4-Jun-12 11:47 

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